I. Field of the Invention
The present invention relates generally to iontophoretic drug delivery systems for transdermal delivery of therapeutic agents and, more particularly, to packaging such systems for long shelf life and easy assembly for use. The system package includes an iontophoretic skin worn patch component that accommodates a power source, electronics, electrodes and a drug pack component that carries a therapeutic agent which is contained as a separate sealed component. The packaged system further provides for ease of assembly at the time of use.
II. Introduction
The process of iontophoresis is well known and has found significant commercial use in the delivery of ionically charged compounds across the skin at the sites of system electrodes of like charge.
Self-contained, wearable iontophoretic systems have been developed in which the electrical circuitry and power supply have been integrated into a single, skin-worn patch. In many of these devices, drug ions are delivered into the body from an aqueous ‘drug’ reservoir contained in the iontophoretic device, and counter ions of opposite charge are delivered from a ‘counter’ reservoir. Because drug/ion solutions are often stored remotely in bulk quantity and introduced to an absorbent layer of the iontophoresis electrode of interest at the time of use, additional steps are necessary to incorporate drug ions and counter ions into the device. However, the electrodes can be easily over-filled or under-filled, thus this aspect requires trained personnel with good technique. Additionally, because the drug solution is stored separately from the electrodes, management of two inventories is required.
To avoid the need for users to incorporate the aqueous drug or ion reservoir at the time of use, the drug solution can be pre-packaged with an electrode, or an aqueous reservoir can be stored in contact with an electrode assembly, and a dry medicament layer introduced to the aqueous reservoir at the time of use. Unfortunately, with either configuration, an electrode is still stored in wet environment, and that and other components may succumb to corrosive deterioration.
For the above and other reasons, co-packaging iontophoretic transdermal drug delivery patches with active pharmaceuticals remains a challenging problem. Because iontophoretic patches contain electrodes and electronics and the drug solution is usually aqueous in nature, without a barrier between the aqueous environment and the electronics, degradation of both the electronics and the drug solution will occur within the desired shelf life, which may be 2 years. A packaging solution that provides a barrier and therefore meets shelf life requirements between the electronics and the drug solution, yet still allows the drug solution and electrodes to be combined in an assembled device at time of use is sought. A solution that not only addresses shelf life stability issues surrounding co-packaging aqueous drug solutions with electrodes and electronic circuits but which also makes it easier for the operator or user to activate and apply the patch is even more desirable.